There are several known methods for producing ceramic-metal composite materials.
Japanese Patent 61/163224 (Sumitomo Electric Industries) of July 23, 1986, discloses a ceramic body having a porosity of 85-90%, infiltrated with aluminum melt under pressure.
Moreover, British Patent 21 48 270 (British Ceramic Research Association) of May 30, 1985, discloses the production of cermets by the infiltration of a porous SiC ceramic having a porosity of 39% with molten aluminum at a temperature of 700.degree. C. and a pressure of 6.72 kpsi.
Other cermets are disclosed in the Czechoslovakian Patent CS 20 61 32 of Oct. 1, 1983. They are produced by evacuating a porous ceramic material, which consists of 90-95% Al.sub.2 O.sub.3, the remainder being SiO.sub.2, and infiltrating it with aluminum or aluminum compounds at temperatures of 700.degree. to 900.degree. C. under an inert gas and at a pressure of more than 1 MPa. Before the infiltration, the molded ceramic article has a porosity of 41%.
In the state of the art therefore, highly porous ceramic materials are infiltrated with a molten metal so that the product produced therefrom has primarily a metallic structure. The properties of this metal-ceramic material are largely metallic in nature so that the hardness, temperature resistance and wear behavior are far below those of strictly ceramic materials.